Fast-neutron capture in 238U and 232Th

Experimental detection techniques employed in the measurements of the 238U(n,#betta#) and 232Th(n,#betta#) cross sections are discussed. The experimental data base is considered and it is concluded that these cross sections are presently known with 5+- in the energy range of greatest importance for LMFBR applications. New measurements will have an insignificant impact on the 238U(n,#betta#) cross sections if they do not achieve an uncertainty of approx. = 2% or less